Taking care of your bones is an important part of staying healthy especially during your breast cancer journey. Some forms of breast cancer treatment are associated with an increased risk of bone thinning. Thin bones are weaker and more likely to break, not just after falls, but even after minimal trauma like bumping into or leaning on something. Maintaining healthy habits like staying active can keep your bones strong, and medications supporting bone health are available if needed.
Some people with advanced breast cancer are diagnosed with bone metastasis, which is when cancer spreads from the breast region to the bones. If you’re experiencing symptoms like bone pain, getting a bone scan can help you and your medical team learn more. Cancer in the bone is different from bone thinning.
Read on to learn more about what you can do to care for your bones after a breast cancer diagnosis and throughout your life.
The structure of bones
Bones are made up of living tissue, which means they can grow, change, and repair themselves. Between birth and adulthood, a process called bone modeling occurs. During this time, our bones grow and increase in mass. Bone mass increases until around the mid-twenties when it reaches its peak. After we reach our peak bone mass, it gradually declines as we age. Women tend to lose bone mass the fastest in the years following menopause. 1 Because of the natural decline in bone mass for both men and women over time, it’s important for everyone to take care of their bones to help slow this loss.
After bone modeling forms our adult skeleton, a process called bone remodeling works to maintain our bones. New bone tissue replaces old tissue, which helps our bones maintain their structure. 1
The outer layer of bone tissue is strong and
hard. Inside our bones, the tissue is spongy. 1
Like a sponge, this tissue has holes in it. As we
age, our body becomes less efficient at
producing new tissue. More holes in the tissue
may develop, or existing holes may increase in
size. This makes our bones less dense. They
become weaker and more likely to fracture
(break). 2 As we’ll discuss later, staying active and making other lifestyle changes can help keep your bones strong.
What is osteoporosis?
The word osteoporosis means “porous bone.” Osteoporosis is a condition where the bones are less dense because the spongy tissue inside the bone is more porous—it has more holes or larger holes. 2 Osteoporotic fractures occur when bones break due to the thinning of the bone.
Osteopenia is a condition that occurs before osteoporosis. This is the lightening of the bones without the thinning we see in osteoporosis. Someone with osteopenia is at risk of developing osteoporosis.
We closely monitor the bones in your hips, wrist, forearms, and back because they are your weight-bearing bones. These bones tend to fracture the most often in people with low bone density. Osteoporosis may cause small compression fractures in the bones of the back, causing a hunched posture.
A bone density scan (also called a DEXA scan) can help diagnose or estimate your risk of developing osteoporosis. This scan uses low-dose X-rays to measure the density of bones in a certain area of the body, often your hip, spine, or forearm. 3 A bone density scan is not the same as a bone scan despite the similar sounding name.
How can breast cancer treatment affect your bones?
The hormone estrogen plays a large role in protecting the bones. Estrogen increases your bone density and prevents bone loss by regulating bone remodeling. 4-5
Some breast cancer treatments work by lowering the estrogen levels in the body. While this is effective at treating the cancer, lower estrogen levels can lead to loss of bone mineral density and increase your risk of bone fractures.
If you start treatment with strong bones, it’s unlikely that the drop in estrogen levels will cause osteoporosis. You may experience a slight decrease in bone mineral density, and you may develop osteopenia. If you’re osteopenic at the start of treatment, your osteopenia may worsen slightly. If you’re very osteopenic, you may develop osteoporosis.
If you already have osteoporosis, you can still receive breast cancer treatment. There are things we can do to support your bone health during treatment, which we will discuss later on.
Chemotherapy affects rapidly dividing cells, including the tissues of the ovary. The ovaries are responsible for producing much of the body’s estrogen. Chemotherapy can stop ovaries from functioning, leading to low estrogen levels and potential bone loss. 6
The loss of function in the ovaries may cause the body to enter menopause. For some people, this change is permanent. For others, this change is temporary, and their ovaries resume function after they finish chemotherapy. 7
Chemotherapy itself may also lead to bone loss. Some chemotherapy drugs, including doxorubicin and cisplatin, can cause bone loss by reducing the levels of calcium in your body. 8
Radiation therapy may cause bone loss in the area of the body receiving the radiation (the radiation field). Scientists think radiation may make bone-building cells less effective while also increasing the production of cells that break down the bone. 8-9 This effect may not appear for several years after treatment. 8
We give endocrine therapy to patients whose tumors have hormone receptors (HR-positive). When hormones like estrogen or progesterone attach to these receptors, they can help the tumor grow. Therefore, we generally treat people with HR-positive tumors with drugs that block or stop the body from using estrogen. These drugs (sometimes called
anti-estrogen drugs) help stop tumor growth by preventing the hormones from attaching to the receptors. 10
Anti-estrogens can cause a loss in bone mineral density. It’s important to know that this loss is reversible. Once you stop taking anti-estrogens, your bone mineral density will increase. It may be permanent in someone who continues endocrine therapy for many years.
Tamoxifen is a drug that blocks estrogen from binding to the estrogen receptors on tumors and signaling them to grow. 10
For premenopausal women, tamoxifen can cause thinning of the bones. Although there is a slight increase in risk, tamoxifen is not likely to cause osteoporosis in premenopausal women unless combined with ovarian suppression. 6 For postmenopausal women, tamoxifen can strengthen the bones. It reduces the risk of osteoporosis by slowing bone loss. 6
Drugs called aromatase inhibitors are often used to treat people who have already gone through menopause at the time of diagnosis or those who are advised to have ovarian suppression (see below).
Although the ovaries produce less estrogen during menopause, a protein in the adrenal glands (glands on top of the kidney) and body fat can produce estrogen. This protein is called aromatase. Aromatase inhibitors stop this protein from producing estrogen.10 This may reduce bone density by lowering estrogen levels in the body. 6
For premenopausal women, taking aromatase inhibitors during ovarian suppression can reduce bone density. 6
Ovarian suppression is a medically induced, reversible menopause. It causes the ovaries to produce less estrogen without causing permanent menopause. 7 Drugs called luteinizing hormone-releasing hormone (LHRH) agonists block the signal that tells the ovaries to make estrogen. 10
Some people may have a surgery called oophorectomy to remove their ovaries altogether. This surgery causes immediate and permanent menopause. Ovarian suppression or removal allows people who are premenopausal to take aromatase inhibitors. 10 There is a risk of reduced bone density with ovarian suppression or removal due to the reduction in estrogen levels in the body. 6
Protecting your bones during breast cancer treatment
Medications called bisphosphonates can help strengthen your bones. They can be given by mouth or IV and can help prevent osteoporotic fractures. If you are under 65 and don’t have any current bone issues, it’s unlikely that you’ll need medication to keep your bones healthy even if you’re on an aromatase inhibitor.
Hormone replacement therapy
Hormone replacement therapy, often given during menopause, can strengthen the bones. However, we do not recommend hormone replacement therapy for people who have had breast cancer, even those with hormone receptor-negative breast cancer. With this type of cancer, giving someone exogenous estrogen (estrogen from outside the body) could cause the cancer to return. Recent research shows that hormone replacement therapy increases the risk of recurrence for people with a history of breast cancer. 11
Smoking can affect estrogen levels, slow the production of the body’s bone-building cells, and reduce calcium absorption. 12 If you’re a smoker, we encourage you to try to quit. If you need support quitting smoking, your doctor can refer you to a helpline or other available resources in your area.
Being mindful of your alcohol consumption can help keep your bones healthy, as alcohol can contribute to bone thinning. Like smoking, heavy alcohol misuse can affect the body’s estrogen levels, bone-building cell production, and calcium absorption. Shortly after someone stops misusing alcohol, the body will begin working to replenish the bone loss. 13 We encourage you to use moderation when using alcohol.
Over time, we tend to become less active. We may also be less active during times of stress. However, it’s important to stay active throughout our lives. Inactivity can cause us to lose bone density and make our bones more vulnerable to breaks.
If your medical team has given you the OK, introducing weight-bearing exercises can help improve your bone density. Bones heal when they have pressure on them. Weight-bearing exercises include:
- walking with a weighted vest
- walking with hand weights
- jogging or power-walking
- lifting weights
- push-ups against a wall
Talk with your medical team to learn more about what weight-bearing exercises may be right for you.
Diet and supplements
Eating foods high in calcium can help keep your bones strong. Calcium in food can come from dairy products, fish like salmon or tuna (bone-in), and green vegetables like spinach. However, it’s harder for our body to absorb the calcium in vegetables than in dairy or fish. Talk to your doctor about calcium supplements if you think you aren’t getting enough calcium in your diet.
Vitamin D helps our body absorb calcium. Many people don’t get enough Vitamin D. As we age, our skin is less efficient at producing it. Eating foods rich in Vitamin D can help. If you eat fish, oily fish such as salmon, tuna, and swordfish are a great source of Vitamin D. Some foods like milk and orange juice are supplemented with Vitamin D. Over-the-counter Vitamin D supplements are also available. Talk to your doctor about whether they might benefit you.
For some, metastasis is another factor that can impact the bones. Metastasis is when cancer spreads from the original tumor to other parts of the body. In people with advanced breast cancer, cancer cells may leave the breast and travel to the bones. This is called bone metastasis. 14
Bone metastasis can occur in any bone, but it occurs most often in the ribs, spine, pelvis, arms, or legs. 15 Bone metastasis may put you at increased risk for bone loss, bone pain, or spinal cord compression. 16
Some people may not feel any symptoms, but symptoms of bone metastasis may include:
- bone pain, which may come and go at first but then become more constant
- urinary or bowel incontinence
- weakness or numbness in an area of the body
- sharp pain or inability to move, which may be a sign of a fracture
- nausea, vomiting, constipation, fatigue, or confusion, which may indicate high levels of calcium in the blood due to bone breakdown 14-15
If you’re experiencing these symptoms, let your medical team know right away. Your doctor may recommend a bone scan. Other scans to detect metastasis include X-ray, CT, PET, or MRI. Your doctor may also recommend blood tests to check for high levels of calcium or other indicators of metastasis. 15
What is a bone scan?
We do bone scans in people with breast cancer or a history of breast cancer. This is different from a bone density scan. A bone scan can identify abnormal areas that suggest cancer might be in the bone.
Bones are constantly remodeling (replacing old tissue with new tissue). When bones abnormally remodel in response to an insult like an injury, fracture, or cancer, the bone will have more turnover. Bone scans can help identify these areas by using a special camera to take pictures of your bones. 16
Who should get a bone scan?
Generally, we don’t recommend a bone scan to people with Stage 0, I, or II breast cancer. For people who are going to get chemotherapy before surgery, we often recommend that you have a bone scan as part of a workup before you start chemotherapy.
If you have symptoms of bone pain, you may be advised to have a bone scan. If you were told that you have Stage IV cancer at the time of your initial diagnosis, a bone scan would be part of your workup.
Sometimes, an MRI can be done in place of a bone scan, but bone scans are generally considered the best option.
What happens during a bone scan?
First, you’ll receive an injection of a radioisotope. This is a low dose of radiation, smaller than you would receive during an X-ray.
After the injection, you’ll need to wait three hours before the scan begins. This is because the radioisotope can take some time to enter your bones. 16 During the three-hour waiting period, you may receive other tests that you need, such as a CAT scan or an ultrasound of your heart (an echocardiogram). If possible, we recommend coordinating your tests so you can get them done during this time.
After three hours, a technician will take pictures of your bones. You’ll be able to see these pictures during the scan. Areas of the bones that use more of the radioisotope will show up as dark spots in the pictures. 16
What does a bone scan tell you?
You may see dark spots on a bone scan due to a fracture, old injury, cancer, or osteoporosis. If the spots appearing on the scan are completely symmetric (in the same spots on the body), that usually indicates normal uptake. It’s also normal to see two dark spots in your kidneys. This is because your kidneys are working to eliminate the radioisotope from your body.
We can’t always tell what’s going on from the picture alone, but cancer sometimes shows a characteristic pattern. The technician performing the scan won’t be able to tell you what the scan shows. A special radiologist trained in nuclear medicine will read the scan and report the interpretation to you.
If the bone scan shows an area of increased uptake, your medical team will compare this result to your history and your symptoms. They will consider whether the scan was done to look for cancer and if you have symptoms in the area where the bone scan shows an abnormality.
If you aren’t known to have advanced cancer, your medical team may recommend a biopsy of the area. Some areas are easier to biopsy than others, and your medical team will discuss this with you.
If you already have advanced cancer and get a bone scan to see how you’re doing, your medical team generally won’t recommend a biopsy. If you’re living with advanced cancer with bone metastasis and the bone scan shows new spots, it’s possible that this may be new cancer.
You should also be aware of a phenomenon called flare. If you’ve been diagnosed with metastatic cancer to the bone and you’re put on treatment, a future bone scan may show increased uptake. New spots may indicate where the bone is healing due to the treatment.
How are bone metastases treated?
Depending on your unique situation, your medical team may recommend some combination of the following to treat bone metastasis:
- endocrine therapy
- targeted therapy
- radiation therapy
- surgery (rarely)
In some cases, we can inject a form of cement into the bone to stabilize it or treat a fracture.15 Your medical team can help you identify the best treatment approach for you and your goals.
Medications used to treat bone metastasis include:
- zoledronic acid
These medications can help prevent bone loss, pain from cancer in the bone, fractures, and spinal cord compression. If you take these medications, your doctor may recommend calcium and Vitamin D supplements. In rare cases, these medications can affect your teeth and jaw. Talk with your doctor to learn more about caring for your teeth while on these medications. 16
Taking care of your bones is important for everyone, as bones tend to lose mass and become more prone to fractures over time. Some breast cancer treatments can increase your risk of bone thinning and weakness. For those with metastatic breast cancer, cancer that reaches the bones can be painful and lead to bone loss or other problems. Bone scans can detect cancer that has spread to the bones. Staying active by incorporating weight-bearing exercises into your routine can help slow bone loss. You can also support your bone health by quitting smoking, monitoring your alcohol use, and getting enough Vitamin D and calcium through your diet or supplements. If needed, your doctor may recommend bone-strengthening medications that can help prevent fractures.
1 Bone biology. International Osteoporosis Foundation.
https://www.osteoporosis.foundation/health-professionals/about-osteoporosis/bone-biology. Accessed December 23, 2022.
2 Osteoporosis. Huffman Spine Clinic. https://huffmanclinic.com/conditions/osteoporosis/.
Published January 4, 2021. Accessed December 23, 2022.
3 Bone density scan (DEXA scan). National Health Service.
https://www.nhs.uk/conditions/dexa-scan/. Published October 5, 2022. Accessed December 23, 2022.
4 Breast cancer and bone loss. Endocrine Society. https://www.endocrine.org/patient-engagement/endocrine-library/breast-cancer-and-bone-loss. Published March 31, 2022. Accessed December 23, 2022.
5 Streicher C, Heyny A, Andrukhova O, et al. Estrogen regulates bone turnover by targeting RANKL expression in bone lining cells. Scientific Reports. 2017;7(1). doi:10.1038/s41598-017-06614-0
6 Bone health and osteoporosis. Breast Cancer Now.
https://breastcancernow.org/information-support/facing-breast-cancer/going-through-treatment-breast-cancer/side-effects/bone-health-osteoporosis. Published December 15, 2022. Accessed December 23, 2022.
7 NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. National Comprehensive Cancer Network. https://www.nccn.org/login?ReturnURL=https://www.nccn.org/professionals/physician_gls/pdf/breast.pdf. Published June 2022. Accessed August 29, 2022.
8 Adams M. 5 questions about bone health and cancer. MD Anderson Cancer Center. https://www.mdanderson.org/cancerwise/5-questions-about-bone-health-and-cancer.h00-159379578.html. Published February 3, 2020. Accessed December 23, 2022.
9 Taxel P, Faircloth E, Idrees S, Van Poznak C. Cancer treatment–induced bone loss in women with breast cancer and men with prostate cancer. Journal of the Endocrine Society. 2018;2(7):574-588. doi:10.1210/js.2018-00052
10 Hormone therapy for breast cancer: Breast cancer treatment. American Cancer Society. https://www.cancer.org/cancer/breastcancer/treatment/hormone-therapy-for-breast-cancer.html. Published October 27, 2021. Accessed October 7, 2022.
11 Poggio F, Del Mastro L, Bruzzone M, et al. Safety of systemic hormone replacement therapy in breast cancer survivors: A systematic review and meta-analysis. Breast Cancer Research and Treatment. 2021;191(2):269-275. doi:10.1007/s10549-021-06436-9
12 What smoking does to your bones. UCI Health.
https://www.ucihealth.org/blog/2018/11/smoking-bone-health. Published November 15, 2018. Accessed December 23, 2022.
13 Reed S. The connection between alcohol misuse and bone health. Alcoholics Anonymous. https://alcoholicsanonymous.com/alcoholism/alcohol-and-bone-health/. Published March 7, 2022. Accessed December 23, 2022.
14 Bone metastasis. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/bone-metastasis/symptoms-causes/syc-20370191. Published April 27, 2022. Accessed December 23, 2022.
15 Bone metastasis. Breastcancer.org. https://www.breastcancer.org/types/metastatic/bone-
metastasis. Published November 18, 2022. Accessed December 23, 2022.
16 NCNN Guidelines for Patients: Invasive Breast Cancer. National Comprehensive Cancer Network. https://www.nccn.org/patients/guidelines/content/PDF/breast-invasive-
patient.pdf. Published 2022. Accessed August 29, 2022.